This is a slightly modified version of the pyflakes.vim script that enables
using pyflakes even with Vim that has no Python support (in case you are, for
any reason, stuck with such an installation of Vim). However, your system still
has to have Python installed.

To work around the unability to call Python code (and thus pyflakes) directly
from vim, pyflakes-vim-nopython spawns an external Python process, writes the
current buffer content to its standard input and reads and parses its standard
output to get the results.

KNOWN ISSUES

* Doesn't work in cygwin when native (Windows) Python is used.
* On Windows, messages are usually not refreshed when changing buffer contents without entering/leaving Insert mode (via "r", "x", etc.)
* In Windows gvim, each pyflakes check causes an annoying blink of the window title bar.
* Running a separate Python process each time the source gets changed is not
very efficient and the time cost may be prohibitive on some machines.

4. Make sure that pyflakes can be found by Python. This is by default done by
enhancing the PYTHONPATH environment variable in the pyflakes-nopython.vim
script, and on most systems that should be sufficient.

Lastly, it is presumed that python can be called as "python" in the system shell.

If you need to change the way the pyflakes-wrapper.py gets invoked, you can
change the s:python_call variable near the top of pyflakes-nopython.vim.